Dr David Jeffery
Dr. David Jeffery has recently been appointed as Lecturer in Wine Science. For the past 5 ½ years he has been with the Australian Wine Research Institute (AWRI) where he worked most recently on grape and wine flavour and aroma research. This has included work developing techniques for the analysis, isolation and synthesis of grape and wine components. Prior to this a particular focus of his research related to the chemistry and sensory properties of polyphenolics in red wine.
David is looking to continue his research into the fundamental structural chemistry of red wine polyphenols as well as taking on new research characterising aroma and flavour precursors in grapes. Of particular interest are amino acid conjugates which are precursors to compounds responsible for the varietal aroma profiles of some white wines. For example, certain wine thiols are responsible for some of the aroma characteristics commonly associated with Sauvignon Blanc (i.e. “tropical” characteristics such as grapefruit, citrus and passionfruit). Two conjugates have been identified, a cysteine conjugate and a glutathione conjugate; how each of these contributes to the aroma profile of a wine is under investigation. The less abundant cysteine conjugate is most likely a breakdown product of the glutathione conjugate, and appears to be more readily utilised during fermentation. In their conjugated forms these thiols do not exhibit their aroma characteristics. Release of the aromatic free volatile forms can occur through processes occurring in the grape and during winemaking (via yeast and microbial enzyme activity). The AWRI is continuing research focussed on the contribution of yeast enzymes to these processes. David is looking at how fruit-derived enzymes, such as glutathione S-transferases (GSTs) and γ-glutamyl transpeptidases (GGTs) contribute to the development of the precursors, along with chemical mechanisms during the winemaking process. Understanding of these processes will enable grape growers and winemakers to have more control over the potential sensory qualities of their fruit and resulting wines.
David has just started some of his lecturing responsibilities and is excited to contribute to the education stream that has served him so well. He will initially be taking over the role of Dr. Graham Jones (recently retired) with lectures in Advances in Wine Science, and Distillation, Fortified and Sparkling Winemaking. David is currently building collaborations in New Zealand and Newcastle to look further into these interesting aspects of flavour and aroma chemistry. He also maintains links with AWRI and is establishing project s related to red wine polyphenols with stakeholders such as DPI Victoria. He is looking for Honours and PhD students interested in doing wine aroma and flavour or polyphenolic research; interested students should contact him via email: david.jeffery@adelaide.edu.au, or phone: 8303 6649.
Written by Bradleigh Hocking
Waite Watch 